Methods and systems for treatment of occipital neuralgia

ABSTRACT

A system for alleviating occipital neuralgia. The system has a needle probe having at least one needle. The at least one needle has a proximal end, a distal end, and a needle lumen therebetween, the needle configured for insertion proximate to a location of the occipital nerve. A cooling fluid supply lumen extends distally within the needle lumen to a distal portion of the needle lumen. A cooling fluid source is coupled to the cooling fluid supply lumen to direct cooling fluid flow into the needle lumen. A controller that has at least one processor configured implements an occipital neuralgia treatment algorithm for controlling the cooling fluid source so that liquid from the cooling flow vaporizes within the needle lumen to provide a treatment phase to location of the occipital nerve such that the occipital neuralgia is mitigated.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a Continuation of U.S. application Ser. No. 15/457,642 filed Mar. 13, 2017 (now U.S. Pat. No. 10,085,789); which is a Divisional of U.S. application Ser. No. 14/218,901 filed Mar. 18, 2014 (now U.S. Pat. No. 10,016,229); which claims benefit of U.S. Provisional Patent Appln No. 61/800,478 filed Mar. 15, 2013; the entire contents of which are incorporated herein by reference in their entirety for all purposes.

BACKGROUND OF THE INVENTION

Occipital neuralgia s a medical condition characterized by chronic pain in the upper neck, back of the head and behind the eyes. Often, occipital nerualgia causes a distinct type of headache characterized by piercing, throbbing, or electric-shock-like chronic pain in the upper neck, back of the head, and behind the ears, usually on one side of the head. Typically, the pain of occipital neuralgia begins in the neck and then spreads upwards. Some individuals will also experience pain in the scalp, forehead, and behind the eyes. Their scalp may also be tender to the touch, and their eyes especially sensitive to light. The location of pain is related to the areas supplied by the greater and lesser occipital nerves, which run from the area where the spinal column meets the neck, up to the scalp at the back of the head. The pain is caused by irritation or injury to the nerves, which can be the result of trauma to the back of the head, pinching of the nerves by overly tight neck muscles, compression of the nerve as it leaves the spine due to osteoarthritis, or tumors or other types of lesions in the neck. Localized inflammation or infection, gout, diabetes, blood vessel inflammation (vasculitis), and frequent lengthy periods of keeping the head in a downward and forward position are also associated with occipital neuralgia. In many cases, however, no cause can be found. A positive response (relief from pain) after an anesthetic nerve block will confirm the diagnosis.

Treatment is generally symptomatic and includes massage and rest. In some cases, antidepressants may be used when the pain is particularly severe. Other treatments may include local nerve blocks and injections of steroids directly into the affected area.

Occipital neuralgia is not a life-threatening condition. Many individuals will improve with therapy involving heat, rest, anti-inflammatory medications, and muscle relaxants. Recovery is usually complete after the bout of pain has ended and the nerve damage repaired or lessened.

BRIEF SUMMARY OF THE INVENTION

Embodiments of the invention are related to a system for alleviating occipital neuralgia. The system can include a needle probe having at least one needle. The at least one needle having a proximal end, a distal end, and a needle lumen therebetween, the needle configured for insertion proximate to a location of the occipital nerve. A cooling fluid supply lumen can extend distally within the needle lumen to a distal portion of the needle lumen. A cooling fluid source can be coupled to the cooling fluid supply lumen to direct cooling fluid flow into the needle lumen. The system can include a controller having at least one processor configured to implement an occipital neuralgia treatment algorithm for controlling the cooling fluid source so that liquid from the cooling flow vaporizes within the needle lumen to provide a treatment cycle to a location of the occipital nerve such that the occipital neuralgia is mitigated.

Embodiments of the invention are also related to a method for alleviating occipital neuralgia. In the method, a distal end of a cryogenic cooling needle probe is positioned proximal to a location of the occipital nerve, the needle probe having at least one needle with a lumen. A treatment is delivered to the target tissue with the cryogenic cooling needle. The treatment includes a cooling phase where cooling fluid flows into the needle lumen so that liquid from the cooling flow vaporizes within the needle lumen to provide cooling to the nerve such that the occipital neuralgia is mitigated.

In many embodiments, a heating element coupled with a proximal portion of the needle, and the heating element can be to deliver heating phases to the skin of the patient. The processor can be configured to control the cooling fluid flow and the heating element in response to operator input, the processor configured to provide the treatment cycle in response to the operator input, the treatment cycle comprising at least one heating phase and one cooling phase.

In many embodiments, the location of the occipital nerve comprises the greater occipital nerve (GON).

In many embodiments, the at least one needle is configured to access the GON.

In many embodiments, the needle probe comprises at pair of needles spaced apart 3-7 mm to flank the GON, each needle being greater than 6 mm in length.

In many embodiments, the location of the occipital nerve comprises the lower occipital nerve (LON).

In many embodiments, the at least one needle is configured to access the LON.

In many embodiments, the needle probe comprises at pair of needles spaced apart 3-7 mm to flank the LON, each needle being greater than 6 mm in length.

In many embodiments, the occipital neuralgia treatment algorithm is configured to cause the needle probe to generate a cryozone having a volume of 65-125 mm³.

In many embodiments, one or a combination of transcutaneous electrical nerve stimulation, percutaneous electrical nerve stimulation, and ultrasound is used to locate the motor nerve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of a self-contained subdermal cryogenic remodeling probe and system, according to some embodiments of the invention;

FIG. 1B is a partially transparent perspective view of the self-contained probe of FIG. 1A, showing internal components of the cryogenic remodeling system and schematically illustrating replacement treatment needles for use with the disposable probe according to some embodiments of the invention;

FIG. 2A schematically illustrates exemplary components that may be included in the treatment system;

FIG. 2B is a cross-sectional view of the system of FIG. 1A, according to some embodiments of the invention;

FIGS. 2C and 2D are cross-sectional views showing exemplary operational modes of the system of FIG. 2B;

FIGS. 3A-3B illustrate exemplary embodiment of a needle probe, according to some embodiments of the invention;

FIGS. 3C-3D illustrate an exemplary embodiment of a detachable probe tip, according to some embodiments of the invention.

FIG. 4A is a flow chart illustrating an exemplary algorithm for heating the needle probe of FIG. 3A, according to some embodiment of the invention;

FIG. 4B is a flow chart schematically illustrating an exemplary method for treatment using the disposable cryogenic probe and system of FIGS. 1A and 1B, according to some embodiments of the invention;

FIG. 5 shows an illustration of the greater occipital nerve;

FIG. 6 shows a greater occipital nerve treatments sites, according to some embodiment of the invention;

FIG. 7 shows the location of the lesser occipital nerve;

FIG. 8 shows a schematic illustration of the courses of the greater and lesser occipital nerves;

FIG. 9 shows a schematic illustration of GON and LON treatment locations, according to some embodiment of the invention;

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides improved medical devices, systems, and methods. Embodiments of the invention may facilitate remodeling of target tissues disposed at and below the skin, optionally treat occipital neuralgia by remodeling tissue of a occipital nerve. Embodiments of the invention may utilize a handheld refrigeration system that can use a commercially available cartridge of fluid refrigerant. Refrigerants well suited for use in handheld refrigeration systems may include nitrous oxide and carbon dioxide. These can achieve temperatures approaching −90° C.

Occipital nerves and associated tissues may be temporarily immobilized using moderately cold temperatures of 10° C. to −5° C. without permanently disabling the tissue structures. Using an approach similar to that employed for identifying structures associated with atrial fibrillation, a needle probe or other treatment device can be used to identify a target tissue structure in a diagnostic mode with these moderate temperatures, and the same probe (or a different probe) can also be used to provide a longer term or permanent treatment, optionally by ablating the target tissue zone and/or inducing apoptosis at temperatures from about −5° C. to about −50° C. In some embodiments, apoptosis may be induced using treatment temperatures from about −1° C. to about −15° C., or from about −1° C. to about −19° C., optionally so as to provide a longer lasting treatment that limits or avoids inflammation and mobilization of skeletal muscle satellite repair cells. In some embodiments, axonotmesis with Wallerian degeneration of a nerve is desired, which may be induced using treatment temperatures from about −20° C. to about −100° C. Hence, the duration of the treatment efficacy of such subdermal cryogenic treatments may be selected and controlled, with colder temperatures, longer treatment times, and/or larger volumes or selected patterns of target tissue determining the longevity of the treatment. Additional description of cryogenic cooling methods and devices may be found in commonly assigned U.S. Pat. No. 7,713,266 entitled “Subdermal Cryogenic Remodeling of Muscle, Nerves, Connective Tissue, and/or Adipose Tissue (Fat)”, U.S. Pat. No. 7,850,683 entitled “Subdermal Cryogenic Remodeling of Muscles, Nerves, Connective Tissue, and/or Adipose Tissue (Fat)”, U.S. patent application Ser. No. 13/325,004 entitled “Method for Reducing Hyperdynamic Facial Wrinkles”, and U.S. Pub. No. 2009/0248001 entitled “Pain Management Using Cryogenic Remodeling,” the full disclosures of which are each incorporated by reference herein.

Cryogenic Systems for Treating Occipital Neuralgia

Referring now to FIGS. 1A and 1B, a system for cryogenic remodeling here comprises a self-contained probe handpiece generally having a proximal end 12 and a distal end 14. A handpiece body or housing 16 has a size and ergonomic shape suitable for being grasped and supported in a surgeon's hand or other system operator. As can be seen most clearly in FIG. 1B, a cryogenic cooling fluid supply 18, a supply valve 32 and electrical power source 20 are found within housing 16, along with a circuit 22 having a processor for controlling cooling applied by self-contained system 10 in response to actuation of an input 24. Alternatively, electrical power can be applied through a cord from a remote power source. Power source 20 also supplies power to heater element 44 in order to heat the proximal region of probe 26 which may thereby help to prevent unwanted skin damage, and a temperature sensor 48 adjacent the proximal region of probe 26 helps monitor probe temperature. Additional details on the heater 44 and temperature sensor 48 are described in greater detail below. When actuated, supply valve 32 controls the flow of cryogenic cooling fluid from fluid supply 18. Some embodiments may, at least in part, be manually activated, such as through the use of a manual supply valve and/or the like, so that processors, electrical power supplies, and the like may not be required.

Extending distally from distal end 14 of housing 16 may be a tissue-penetrating cryogenic cooling probe 26. Probe 26 is thermally coupled to a cooling fluid path extending from cooling fluid source 18, with the exemplary probe comprising a tubular body receiving at least a portion of the cooling fluid from the cooling fluid source therein. The exemplary probe 26 may comprise a 30 g needle having a sharpened distal end that is axially sealed. Probe 26 may have an axial length between distal end 14 of housing 16 and the distal end of the needle of between about 0.5 mm and 15 cm, preferably having a length from about 3 mm to about 10 mm. Such needles may comprise a stainless steel tube with an inner diameter of about 0.006 inches and an outer diameter of about 0.012 inches, while alternative probes may comprise structures having outer diameters (or other lateral cross-sectional dimensions) from about 0.006 inches to about 0.100 inches. Generally, needle probe 26 may comprise a 16 g or smaller size needle, often comprising a 20 g needle or smaller, typically comprising a 25, 26, 27, 28, 29, or 30 g or smaller needle.

In some embodiments, probe 26 may comprise two or more needles arranged in a linear array, such as those disclosed in previously incorporated U.S. Pat. No. 7,850,683. Another exemplary embodiment of a probe having multiple needle probe configurations allow the cryogenic treatment to be applied to a larger or more specific treatment area. Other needle configurations that facilitate controlling the depth of needle penetration and insulated needle embodiments are disclosed in commonly assigned U.S. Patent Publication No. 2008/0200910 entitled “Replaceable and/or Easily Removable Needle Systems for Dermal and Transdermal Cryogenic Remodeling,” the entire content of which is incorporated herein by reference. Multiple needle arrays may also be arrayed in alternative configurations such as a triangular or square array.

Arrays may be designed to treat a particular region of tissue, or to provide a uniform treatment within a particular region, or both. In some embodiments needle 26 may be releasably coupled with body 16 so that it may be replaced after use with a sharper needle (as indicated by the dotted line) or with a needle having a different configuration. In exemplary embodiments, the needle may be threaded into the body, press fit into an aperture in the body or have a quick disconnect such as a detent mechanism for engaging the needle with the body. A quick disconnect with a check valve may be advantageous since it may permit decoupling of the needle from the body at any time without excessive coolant discharge. This can be a useful safety feature in the event that the device fails in operation (e.g. valve failure), allowing an operator to disengage the needle and device from a patient's tissue without exposing the patient to coolant as the system depressurizes. This feature may also be advantageous because it allows an operator to easily exchange a dull needle with a sharp needle in the middle of a treatment. One of skill in the art will appreciate that other coupling mechanisms may be used.

Addressing some of the components within housing 16, the exemplary cooling fluid supply 18 may comprise a canister, sometimes referred to herein as a cartridge, containing a liquid under pressure, with the liquid preferably having a boiling temperature of less than 37° C. at one atmosphere of pressure. When the fluid is thermally coupled to the tissue-penetrating probe 26, and the probe is positioned within the patient so that an outer surface of the probe is adjacent to a target tissue, the heat from the target tissue evaporates at least a portion of the liquid and the enthalpy of vaporization cools the target tissue. A supply valve 32 may be disposed along the cooling fluid flow path between canister 18 and probe 26, or along the cooling fluid path after the probe so as to limit coolant flow thereby regulating the temperature, treatment time, rate of temperature change, or other cooling characteristics. The valve will often be powered electrically via power source 20, per the direction of processor 22, but may at least in part be manually powered. The exemplary power source 20 comprises a rechargeable or single-use battery. Additional details about valve 32 are disclosed below and further disclosure on the power source 20 may be found in commonly assigned Int'l Pub. No. WO 2010/075438 entitled “Integrated Cryosurgical Probe Package with Fluid Reservoir and Limited Electrical Power Source,” the entire contents of which are incorporated herein by reference.

The exemplary cooling fluid supply 18 may comprise a single-use canister. Advantageously, the canister and cooling fluid therein may be stored and/or used at (or even above) room temperature. The canister may have a frangible seal or may be refillable, with the exemplary canister containing liquid nitrous oxide, N₂O. A variety of alternative cooling fluids might also be used, with exemplary cooling fluids including fluorocarbon refrigerants and/or carbon dioxide. The quantity of cooling fluid contained by canister 18 will typically be sufficient to treat at least a significant region of a patient, but will often be less than sufficient to treat two or more patients. An exemplary liquid N₂O canister might contain, for example, a quantity in a range from about 1 gram to about 40 grams of liquid, more preferably from about 1 gram to about 35 grams of liquid, and even more preferably from about 7 grams to about 30 grams of liquid.

Processor 22 will typically comprise a programmable electronic microprocessor embodying machine readable computer code or programming instructions for implementing one or more of the treatment methods described herein. The microprocessor will typically include or be coupled to a memory (such as a non-volatile memory, a flash memory, a read-only memory (“ROM”), a random access memory (“RAM”), or the like) storing the computer code and data to be used thereby, and/or a recording media (including a magnetic recording media such as a hard disk, a floppy disk, or the like; or an optical recording media such as a CD or DVD) may be provided. Suitable interface devices (such as digital-to-analog or analog-to-digital converters, or the like) and input/output devices (such as USB or serial I/O ports, wireless communication cards, graphical display cards, and the like) may also be provided. A wide variety of commercially available or specialized processor structures may be used in different embodiments, and suitable processors may make use of a wide variety of combinations of hardware and/or hardware/software combinations. For example, processor 22 may be integrated on a single processor board and may run a single program or may make use of a plurality of boards running a number of different program modules in a wide variety of alternative distributed data processing or code architectures.

Referring now to FIG. 2A, schematic 11 shows a simplified diagram of cryogenic cooling fluid flow and control. The flow of cryogenic cooling fluid from fluid supply 18 may be controlled by a supply valve 32. Supply valve 32 may comprise an electrically actuated solenoid valve, a motor actuated valve or the like operating in response to control signals from controller 22, and/or may comprise a manual valve. Exemplary supply valves may comprise structures suitable for on/off valve operation, and may provide venting of the fluid source and/or the cooling fluid path downstream of the valve when cooling flow is halted so as to limit residual cryogenic fluid vaporization and cooling. Additionally, the valve may be actuated by the controller in order to modulate coolant flow to provide high rates of cooling in some instances where it is desirable to promote necrosis of tissue such as in malignant lesions and the like or slow cooling which promotes ice formation between cells rather than within cells when necrosis is not desired. More complex flow modulating valve structures might also be used in other embodiments. For example, other applicable valve embodiments are disclosed in previously incorporated U.S. Pub. No. 2008/0200910.

Still referring to FIG. 2A, an optional heater (not illustrated) may be used to heat cooling fluid supply 18 so that heated cooling fluid flows through valve 32 and through a lumen 34 of a cooling fluid supply tube 36. In some embodiments a safety mechanism can be included so that the cooling supply is not overheated. Examples of such embodiments are disclosed in commonly assigned International Publication No. WO 2010075438, the entirety of which is incorporated by reference herein.

Supply tube 36 is, at least in part, disposed within a lumen 38 of needle 26, with the supply tube extending distally from a proximal end 40 of the needle toward a distal end 42. The exemplary supply tube 36 comprises a fused silica tubular structure (not illustrated) having a polymer coating and extending in cantilever into the needle lumen 38. Supply tube 36 may have an inner lumen with an effective inner diameter of less than about 200 μm, the inner diameter often being less than about 100 μm, and typically being less than about 40 μm. Exemplary embodiments of supply tube 36 have inner lumens of between about 15 and 50 μm, such as about 30 μm. An outer diameter or size of supply tube 36 will typically be less than about 1000 μm, often being less than about 800 μm, with exemplary embodiments being between about 60 and 150 μm, such as about 90 μm or 105 μm. The tolerance of the inner lumen diameter of supply tubing 36 will preferably be relatively tight, typically being about +/−10 μm or tighter, often being +/−5 μm or tighter, and ideally being +/−3 μm or tighter, as the small diameter supply tube may provide the majority of (or even substantially all of) the metering of the cooling fluid flow into needle 26. Additional details on various aspects of needle 26 along with alternative embodiments and principles of operation are disclosed in greater detail in U.S. Patent Publication No. 2008/0154254 entitled “Dermal and Transdermal Cryogenic Microprobe Systems and Methods,” the entire contents of which are incorporated herein by reference. Previously incorporated U.S. Patent Publication No. 2008/0200910 also discloses additional details on the needle 26 along with various alternative embodiments and principles of operation.

The cooling fluid injected into lumen 38 of needle 26 will typically comprise liquid, though some gas may also be injected. At least some of the liquid vaporizes within needle 26, and the enthalpy of vaporization cools the needle and also the surrounding tissue engaged by the needle. An optional heater 44 (illustrated in FIG. 1B) may be used to heat the proximal region of the needle in order to prevent unwanted skin damage in this area, as discussed in greater detail below. Controlling a pressure of the gas/liquid mixture within needle 26 substantially controls the temperature within lumen 38, and hence the treatment temperature range of the tissue. A relatively simple mechanical pressure relief valve 46 may be used to control the pressure within the lumen of the needle, with the exemplary valve comprising a valve body such as a ball bearing, urged against a valve seat by a biasing spring. An exemplary relief valve is disclosed in U.S. Provisional Patent Application No. 61/116,050 previously incorporated herein by reference. Thus, the relief valve may allow better temperature control in the needle, minimizing transient temperatures. Further details on exhaust volume are disclosed in previously incorporated U.S. Pat. Pub. No. 2008/0200910.

The heater 44 may be thermally coupled to a thermally responsive element 50, which is supplied with power by the controller 22 and thermally coupled to a proximal portion of the needle 26. The thermally responsive element 50 can be a block constructed from a material of high thermal conductivity and low heat capacity, such as aluminum. A first temperature sensor 52 (e.g., thermistor, thermocouple) can also be thermally coupled the thermally responsive element 50 and communicatively coupled to the controller 22. A second temperature sensor 53 can also be positioned near the heater 44, for example, such that the first temperature sensor 52 and second temperature sensor 53 are placed in different positions within the thermally responsive element 50. In some embodiments, the second temperature sensor 53 is placed closer to a tissue contacting surface than the first temperature sensor 52 is placed in order to provide comparative data (e.g., temperature differential) between the sensors 52, 53. The controller 22 can be configured to receive temperature information of the thermally responsive element 50 via the temperature sensor 52 in order to provide the heater 44 with enough power to maintain the thermally responsive element 50 at a particular temperature.

The controller 22 can be further configured to monitor power draw from the heater 44 in order to characterize tissue type, perform device diagnostics, and/or provide feedback for a tissue treatment algorithm. This can be advantageous over monitoring temperature alone, since power draw from the heater 44 can vary greatly while temperature of the thermally responsive element 50 remains relatively stable. For example, during treatment of target tissue, maintaining the thermally responsive element 50 at 40° C. during a cooling phase may take 1.0 W initially (for a needle <10 mm in length) and is normally expected to climb to 1.5 W after 20 seconds, due to the needle 26 drawing in surrounding heat. An indication that the heater is drawing 2.0 W after 20 seconds to maintain 40° C. can indicate that an aspect of the system 10 is malfunctioning and/or that the needle 26 is incorrectly positioned. Correlations with power draw and correlated device and/or tissue conditions can be determined experimentally to determine acceptable treatment power ranges.

In some embodiments, it may be preferable to limit frozen tissue that is not at the treatment temperature, i.e., to limit the size of a formed cooling zone within tissue. Such cooling zones may be associated with a particular physical reaction, such as the formation of an ice-ball, or with a particular temperature profile or temperature volume gradient required to therapeutically affect the tissue therein. To achieve this, metering coolant flow could maintain a large thermal gradient at its outside edges. This may be particularly advantageous in applications for creating an array of connected cooling zones (i.e., fence) in a treatment zone, as time would be provided for the treatment zone to fully develop within the fenced in portion of the tissue, while the outer boundaries maintained a relatively large thermal gradient due to the repeated application and removal of refrigeration power. This could provide a mechanism within the body of tissue to thermally regulate the treatment zone and could provide increased ability to modulate the treatment zone at a prescribed distance from the surface of the skin. A related treatment algorithm could be predefined, or it could be in response to feedback from the tissue.

Such feedback could be temperature measurements from the needle 26, or the temperature of the surface of the skin could be measured. However, in many cases monitoring temperature at the needle 26 is impractical due to size constraints. To overcome this, operating performance of the sensorless needle 26 can be interpolated by measuring characteristics of thermally coupled elements, such as the thermally responsive element 50.

Additional methods of monitoring cooling and maintaining an unfrozen portion of the needle include the addition of a heating element and/or monitoring element into the needle itself. This could consist of a small thermistor or thermocouple, and a wire that could provide resistive heat. Other power sources could also be applied such as infrared light, radiofrequency heat, and ultrasound. These systems could also be applied together dependent upon the control of the treatment zone desired.

Alternative methods to inhibit excessively low transient temperatures at the beginning of a refrigeration cycle might be employed instead of or together with the limiting of the exhaust volume. For example, the supply valve 32 might be cycled on and off, typically by controller 22, with a timing sequence that would limit the cooling fluid flowing so that only vaporized gas reached the needle lumen 38 (or a sufficiently limited amount of liquid to avoid excessive dropping of the needle lumen temperature). This cycling might be ended once the exhaust volume pressure was sufficient so that the refrigeration temperature would be within desired limits during steady state flow. Analytical models that may be used to estimate cooling flows are described in greater detail in previously incorporated U.S. Patent Pub. No. 2008/0154254.

FIG. 2B shows a cross-section of the housing 16. This embodiment of the housing 16 may be powered by an external source, hence the attached cable, but could alternatively include a portable power source. As shown, the housing includes a cartridge holder 50. The cartridge holder 50 includes a cartridge receiver 52, which may be configured to hold a pressured refrigerant cartridge 18. The cartridge receiver 52 includes an elongated cylindrical passage 54, which is dimensioned to hold a commercially available cooling fluid cartridge 18. A distal portion of the cartridge receiver 52 includes a filter device 56, which has an elongated conical shape. In some embodiments, the cartridge holder 50 may be largely integrated into the housing 16 as shown, however, in alternative embodiments, the cartridge holder 50 is a wholly separate assembly, which may be pre-provided with a coolant fluid source 18.

The filter device 56 may fluidly couple the coolant fluid source (cartridge) 18 at a proximal end to the valve 32 at a distal end. The filter device 56 may include at least one particulate filter 58. In the shown embodiment, a particulate filter 58 at each proximal and distal end of the filter device 56 may be included. The particulate filter 58 can be configured to prevent particles of a certain size from passing through. For example, the particulate filter 58 can be constructed as a microscreen having a plurality of passages less than 2 microns in width, and thus particles greater than 2 microns would not be able to pass.

The filter device 56 also includes a molecular filter 60 that is configured to capture fluid impurities. In some embodiments, the molecular filter 60 is a plurality of filter media (e.g., pellets, powder, particles) configured to trap molecules of a certain size. For example, the filter media can comprise molecular sieves having pores ranging from 1-20 Å. In another example, the pores have an average size of 5 Å. The molecular filter 60 can have two modalities. In a first mode, the molecular filter 60 will filter fluid impurities received from the cartridge 18. However, in another mode, the molecular filter 60 can capture impurities within the valve 32 and fluid supply tube 36 when the system 10 is not in use, i.e., when the cartridge 18 is not fluidly connected to the valve 32.

Alternatively, the filter device 56 can be constructed primarily from ePTFE (such as a GORE material), sintered polyethylene (such as made by POREX), or metal mesh. The pore size and filter thickness can be optimized to minimize pressure drop while capturing the majority of contaminants. These various materials can be treated to make it hydrophobic (e.g., by a plasma treatment) and/or oleophobic so as to repel water or hydrocarbon contaminants.

It has been found that in some instances fluid impurities may leach out from various aspects of the system 10. These impurities can include trapped moisture in the form of water molecules and chemical gasses. The presence of these impurities is believed to hamper cooling performance of the system 10. The filter device 56 can act as a desiccant that attracts and traps moisture within the system 10, as well as chemicals out gassed from various aspects of the system 10. Alternately the various aspects of the system 10 can be coated or plated with impermeable materials such as a metal.

As shown in FIG. 2B and in more detail in FIG. 2C and FIG. 2D, the cartridge 18 can be held by the cartridge receiver 52 such that the cartridge 18 remains intact and unpunctured. In this inactive mode, the cartridge may not be fluidly connected to the valve 32. A removable cartridge cover 62 can be attached to the cartridge receiver 52 such that the inactive mode is maintained while the cartridge is held by the system 10.

In use, the cartridge cover 62 can be removed and supplied with a cartridge containing a cooling fluid. The cartridge cover 62 can then be reattached to the cartridge receiver 52 by turning the cartridge cover 62 until female threads 64 of the cartridge cover 62 engage with male threads of the cartridge receiver 52. The cartridge cover 62 can be turned until resilient force is felt from an elastic seal 66, as shown in FIG. 2C. To place the system 10 into use, the cartridge cover 62 can be further turned until the distal tip of the cartridge 18 is punctured by a puncture pin connector 68, as shown in FIG. 2D. Once the cartridge 18 is punctured, cooling fluid may escape the cartridge by flowing through the filter device 56, where the impurities within the cooling fluid may be captured. The purified cooling fluid then passes to the valve 32, and onto the coolant supply tube 36 to cool the probe 26. In some embodiments the filter device, or portions thereof, may be replaceable.

In some embodiments, the puncture pin connector 68 can have a two-way valve (e.g., ball/seat and spring) that is closed unless connected to the cartridge. Alternately, pressure can be used to open the valve. The valve closes when the cartridge is removed. In some embodiments, there may be a relief valve piloted by a spring which is balanced by high-pressure nitrous when the cartridge is installed and the system is pressurized, but allows the high-pressure cryogen to vent when the cryogen is removed. In addition, the design can include a vent port that vents cold cryogen away from the cartridge port. Cold venting cryogen locally can cause condensation in the form of liquid water to form from the surrounding environment. Liquid water or water vapor entering the system can hamper the cryogenic performance. Further, fluid carrying portions of the cartridge receiver 52 can be treated (e.g., plasma treatment) to become hydrophobic and/or oleophobic so as to repel water or hydrocarbon contaminants.

Turning now to FIG. 3A and FIG. 3B, an exemplary embodiment of probe 300 having multiple needles 302 is described. In FIG. 3A, probe housing 316 includes threads 306 that allow the probe to be threadably engaged with the housing 16 of a cryogenic device. O-rings 308 fluidly seal the probe housing 316 with the device housing 16 and prevent coolant from leaking around the interface between the two components. Probe 300 includes an array of three distally extending needle shafts 302, each having a sharpened, tissue penetrating tip 304. Using three linearly arranged needles allows a greater area of tissue to be treated as compared with a single needle. In use, coolant flows through lumens 310 into the needle shafts 302 thereby cooling the needle shafts 302. Ideally, only the distal portion of the needle shaft 302 would be cooled so that only the target tissue receives the cryogenic treatment. However, as the cooling fluid flows through the probe 300, probe temperature decreases proximally along the length of the needle shafts 302 towards the probe hub 318. The proximal portion of needle shaft 302 and the probe hub 318 contact skin and may become very cold (e.g. −20° C. to −25° C.) and this can damage the skin in the form of blistering or loss of skin pigmentation. Therefore it would be desirable to ensure that the proximal portion of needle shaft 302 and hub 318 remains warmer than the distal portion of needle shaft 302. A proposed solution to this challenge is to include a heater element 314 that can heat the proximal portion of needle shaft 302 and an optional temperature sensor 312 to monitor temperature in this region. To further this, a proximal portion of the needle shaft 302 can be coated with a highly thermally conductive material, e.g., gold, that is conductively coupled to both the needle shaft 302 and heater element 314. Details of this construction are disclosed below.

In the exemplary embodiment of FIG. 3A, resistive heater element 314 is disposed near the needle hub 318 and near a proximal region of needle shaft 302. The resistance of the heater element is preferably 1Ω to 1K Ω, and more preferably from 5Ω to 50Ω. Additionally, a temperature sensor 312 such as a thermistor or thermocouple is also disposed in the same vicinity. Thus, during a treatment as the needles cool down, the heater 314 may be turned on in order to heat the hub 318 and proximal region of needle shaft 302, thereby preventing this portion of the device from cooling down as much as the remainder of the needle shaft 302. The temperature sensor 312 may provide feedback to controller 22 and a feedback loop can be used to control the heater 314. The cooling power of the nitrous oxide may eventually overcome the effects of the heater, therefore the microprocessor may also be programmed with a warning light and/or an automatic shutoff time to stop the cooling treatment before skin damage occurs. An added benefit of using such a heater element is the fact that the heat helps to moderate the flow of cooling fluid into the needle shaft 302 helping to provide more uniform coolant mass flow to the needles shaft 302 with more uniform cooling resulting.

The embodiment of FIG. 3A illustrates a heater fixed to the probe hub. In other embodiments, the heater may float, thereby ensuring proper skin contact and proper heat transfer to the skin. Examples of floating heaters are disclosed in commonly assigned Int'l Pub. No. WO 2010/075448 entitled “Skin Protection for Subdermal Cryogenic Remodeling for Cosmetic and Other Treatments,” the entirety of which is incorporated by reference herein.

In this exemplary embodiment, three needles are illustrated. One of skill in the art will appreciate that a single needle may be used, as well as two, four, five, six, or more needles may be used. When a plurality of needles are used, they may be arranged in any number of patterns. For example, a single linear array may be used, or a two dimensional or three dimensional array may be used. Examples of two dimensional arrays include any number of rows and columns of needles (e.g. a rectangular array, a square array, elliptical, circular, triangular, etc.), and examples of three dimensional arrays include those where the needle tips are at different distances from the probe hub, such as in an inverted pyramid shape.

FIG. 3B illustrates a cross-section of the needle shaft 302 of needle probe 300. The needle shaft can be conductively coupled (e.g., welded, conductively bonded, press fit) to a conductive heater 314 to enable heat transfer therebetween. The needle shaft 302 is generally a small (e.g., 20-30 gauge) closed tip hollow needle, which can be between about 0.2 mm and 15 cm, preferably having a length from about 0.3 cm to about 1.5 cm. The conductive heater element 314 can be housed within a conductive block 315 of high thermally conductive material, such as aluminum and include an electrically insulated coating, such as Type III anodized coating to electrically insulate it without diminishing its heat transfer properties. The conductive block 315 can be heated by a resister or other heating element (e.g. cartridge heater, nichrome wire, etc.) bonded thereto with a heat conductive adhesive, such as epoxy. A thermistor can be coupled to the conductive block 315 with heat conductive epoxy allows temperature monitoring. Other temperature sensors may also be used, such as a thermocouple.

A cladding 320 of conductive material is directly conductively coupled to the proximal portion of the shaft of the needle 302, which can be stainless steel. In some embodiments, the cladding 320 is a layer of gold, or alloys thereof, coated on the exterior of the proximal portion of the needle shaft 302. In some embodiments, the exposed length of cladding 320 on the proximal portion of the needle is 2-100 mm. In some embodiments, the cladding 320 can be of a thickness such that the clad portion has a diameter ranging from 0.017-0.020 in., and in some embodiments 0.0182 in. Accordingly, the cladding 320 can be conductively coupled to the material of the needle 302, which can be less conductive, than the cladding 320. The cladding 320 may modify the lateral force required to deflect or bend the needle 26. Cladding 320 may be used to provide a stiffer needle shaft along the proximal end in order to more easily transfer force to the leading tip during placement and allow the distal portion of the needle to deflect more easily when it is dissecting a tissue interface within the body. The stiffness of needle 26 can vary from one end to the other end by other means such as material selection, metal tempering, variation of the inner diameter of the needle 26, or segments of needle shaft joined together end-to-end to form one contiguous needle 26. In some embodiments, increasing the stiffness of the distal portion of the needle 26 can be used to flex the proximal portion of the needle to access difficult treatment sites as in the case of occipital neuralgia where bending of the needle outside the body may be used to access a target peripheral nerve along the desired tissue plane.

In some embodiments, the cladding 320 can include sub-coatings (e.g., nickel) that promote adhesion of an outer coating that would otherwise not bond well to the needle shaft 302. Other highly conductive materials can be used as well, such as copper, silver, aluminum, and alloys thereof. In some embodiments, a protective polymer or metal coating can cover the cladding to promote biocompatibility of an otherwise non-biocompatible but highly conductive cladding material. Such a biocompatible coating however, would be applied to not disrupt conductivity between the conductive block 315. In some embodiments, an insulating layer, such as a ceramic material, is coated over the cladding 320, which remains conductively coupled to the needle shaft 302.

FIGS. 3C and 3D illustrates a detachable probe tip 322 having a hub connector 324 and an elongated probe 326. The probe tip 322 shares much of its construction with probe 300. However, the elongated probe 326 features a blunt tip 328 that is adapted for blunt dissection of tissue. The blunt tip 328 can feature a full radius tip, less than a full radius tip, or conical tip. In some embodiments, a dulled or truncated needle is used. The elongated probe 326 can be greater than 20 gauge in size, and in some embodiments range in size from 25-30 gauge. As with the embodiments described above, an internal supply tube 330 extends in cantilever. However, the exit of the supply tube 330 can be disposed at positions within the elongated probe 326 other than proximate the blunt tip 328. Further, the supply tube 330 can be adapted to create an elongated zone of cooling, e.g., by having multiple exit points for cryofluid to exit from.

The elongated probe 326 and supply tube 330 may be configured to resiliently bend in use, throughout their length at angles approaching 120°, with a 5-10 mm bend radius. This may be very challenging considering the small sizes of the elongated probe 326 and supply tube 330, and also considering that the supply tube 330 is often constructed from fused silica. Accordingly, the elongated probe 326 can be constructed from a resilient material, such as stainless steel, and of a particular diameter and wall thickness [0.004 to 1.0 mm], such that the elongated probe in combination with the supply tube 330 is not overly resilient so as to overtly resist manipulation, but sufficiently strong so as to prevent kinking that can result in coolant escaping. For example, the elongated probe can be 15 gauge or smaller in diameter, even ranging from 20-30 gauge in diameter. The elongated probe can have a very disparate length to diameter ratio, for example, the elongated probe can be greater than 30 mm in length, and in some cases range from 30-100 mm in length. To further the aforementioned goals, the supply tube 330 can include a polymer coating 332, such as a polyimide coating that terminates approximately halfway down its length, to resist kinking and aid in resiliency. The polymer coating 332 can be a secondary coating over a primary polyimide coating that extends fully along the supply tube. However, it should be understood that the coating is not limited to polyimide, and other suitable materials can be used. In some embodiments, the flexibility of the elongated probe 326 will vary from the proximal end to the distal end. For example, by creating certain portions that have more or less flexibility than others. This may be done, for example, by modifying wall thickness, adding material (such as the cladding discussed above), and/or heat treating certain portions of the elongated probe 326 and/or supply tube 330. For example, decreasing the flexibility of elongated probe 326 along the proximal end can improve the transfer of force from the hand piece to the elongated probe end for better feel and easier tip placement for treatment. The elongated probe and supply line 330 are may be configured to resiliently bend in use to different degrees along the length at angles approaching 120°, with a varying bend radius as small as 5 mm. In some embodiments, the elongated probe 326 will have external markings along the needle shaft indicating the length of needle inserted into the tissue.

An exemplary algorithm 400 for controlling the heater element 314, and thus for transferring heat to the cladding 320, is illustrated in FIG. 4A. In FIG. 4A, the start of the interrupt service routine (ISR) 402 begins with reading the current needle hub temperature 404 using a temperature sensor such as a thermistor or thermocouple disposed near the needle hub. The time of the measurement is also recorded. This data is fed back to controller 22 where the slope of a line connecting two points is calculated. The first point in the line is defined by the current needle hub temperature and time of its measurement and the second point consists of a previous needle hub temperature measurement and its time of measurement. Once the slope of the needle hub temperature curve has been calculated 406, it is also stored 408 along with the time and temperature data. The needle hub temperature slope is then compared with a slope threshold value 410. If the needle hub temperature slope is less than the threshold value then a treating flag is activated 412 and the treatment start time is noted and stored 414. If the needle hub slope is greater than or equal to the slope threshold value 410, an optional secondary check 416 may be used to verify that cooling has not been initiated. In step 416, absolute needle hub temperature is compared to a temperature threshold. If the hub temperature is less than the temperature threshold, then the treating flag is activated 412 and the treatment start time is recorded 414 as previously described. As an alternative, the shape of the slope could be compared to a norm, and an error flag could be activated for an out of norm condition. Such a condition could indicate the system was not heating or cooling sufficiently. The error flag could trigger an automatic stop to the treatment with an error indicator light. Identifying the potential error condition and possibly stopping the treatment may prevent damage to the proximal tissue in the form of too much heat, or too much cooling to the tissue. The algorithm preferably uses the slope comparison as the trigger to activate the treatment flag because it is more sensitive to cooling conditions when the cryogenic device is being used rather than simply measuring absolute temperature. For example, a needle probe exposed to a cold environment would gradually cool the needle down and this could trigger the heater to turn on even though no cryogenic cooling treatment was being conducted. The slope more accurately captures rapid decreases in needle temperature as are typically seen during cryogenic treatments.

When the treatment flag is activated 418 the needle heater is enabled 420 and heater power may be adjusted based on the elapsed treatment time and current needle hub temperature 422. Thus, if more heat is required, power is increased and if less heat is required, power is decreased. Whether the treatment flag is activated or not, as an additional safety mechanism, treatment duration may be used to control the heater element 424. As mentioned above, eventually, cryogenic cooling of the needle will overcome the effects of the heater element. In that case, it would be desirable to discontinue the cooling treatment so that the proximal region of the probe does not become too cold and cause skin damage. Therefore, treatment duration is compared to a duration threshold value in step 424. If treatment duration exceeds the duration threshold then the treatment flag is cleared or deactivated 426 and the needle heater is deactivated 428. If the duration has not exceeded the duration threshold 424 then the interrupt service routine ends 430. The algorithm then begins again from the start step 402. This process continues as long as the cryogenic device is turned on.

Preferred ranges for the slope threshold value may range from about −5° C. per second to about −90° C. per second and more preferably range from about −30° C. per second to about −57° C. per second. Preferred ranges for the temperature threshold value may range from about 15° C. to about 0° C., and more preferably may range from about 0° C. to about 10° C. Treatment duration threshold may range from about 15 seconds to about 75 seconds.

It should be appreciated that the specific steps illustrated in FIG. 4A provide a particular method of heating a cryogenic probe, according to an embodiment of the present invention. Other sequences of steps may also be performed according to alternative embodiments. For example, alternative embodiments of the present invention may perform the steps outlined above in a different order. Moreover, the individual steps illustrated in FIG. 13 may include multiple sub-steps that may be performed in various sequences as appropriate to the individual step. Furthermore, additional steps may be added or removed depending on the particular applications.

The heating algorithm may be combined with a method for treating a patient. Referring now to FIG. 4B, a method 100 facilitates treating a patient using a cryogenic cooling system having a reusable or disposable handpiece either of which that can be self-contained or externally powered with replaceable needles such as those of FIG. 1B and a limited capacity battery or metered electrical supply. Method 100 generally begins with a determination 110 of the desired tissue therapy and results, such as the inhibition of pain from a particular site. Appropriate target tissues for treatment are identified 112 (a tissue that transmits the pain signal), allowing a target treatment depth, target treatment temperature profile, or the like to be determined. Step 112 may include performing a tissue characterization and/or device diagnostic algorithm, based on power draw of system 10, for example.

The application of the treatment algorithm 114 may include the control of multiple parameters such as temperature, time, cycling, pulsing, and ramp rates for cooling or thawing of treatment areas. In parallel with the treatment algorithm 114, one or more power monitoring algorithms 115 can be implemented. An appropriate needle assembly can then be mounted 116 to the handpiece, with the needle assembly optionally having a needle length, skin surface cooling chamber, needle array, and/or other components suitable for treatment of the target tissues. Simpler systems may include only a single needle type, and/or a first needle assembly mounted to the handpiece.

Pressure, heating, cooling, or combinations thereof may be applied 118 to the skin surface adjacent the needle insertion site before, during, and/or after insertion 120 and cryogenic cooling 122 of the needle and associated target tissue. Non-target tissue directly above the target tissue can be protected by directly conducting energy in the form of heat to the cladding on a proximal portion of the needle shaft during cooling. Upon completion of the cryogenic cooling phase the needles will need additional “thaw” time 123 to thaw from the internally created cooling zone to allow for safe removal of the probe without physical disruption of the target tissues, which may include, but not be limited to nerves, muscles, blood vessels, or connective tissues. This thaw time can either be timed with the refrigerant valve shut-off for as short a time as possible, preferably under 15 seconds, more preferably under 5 seconds, manually or programmed into the controller to automatically shut-off the valve and then pause for a chosen time interval until there is an audible or visual notification of treatment completion.

Heating of the needle may be used to prevent unwanted skin damage using the apparatus and methods previously described. The needle can then be retracted 124 from the target tissue. If the treatment is not complete 126 and the needle is not yet dull 128, pressure and/or cooling can be applied to the next needle insertion location site 118, and the additional target tissue treated. However, as small gauge needles may dull after being inserted only a few times into the skin, any needles that are dulled (or otherwise determined to be sufficiently used to warrant replacement, regardless of whether it is after a single insertion, 5 insertions, or the like) during the treatment may be replaced with a new needle 116 before the next application of pressure/cooling 118, needle insertion 120, and/or the like. Once the target tissues have been completely treated, or once the cooling supply canister included in the self-contained handpiece is depleted, the used canister and/or needles can be disposed of 130. The handpiece may optionally be discarded.

As shown at FIG. 5, the greater occipital nerve (GON) is a spinal nerve, specifically the medial branch of the dorsal primary ramus of cervical spinal nerve. This nerve arises from between the first and second cervical vertebrae, along with the lesser occipital nerve. It ascends after emerging from the suboccipital triangle obliquely between the inferior oblique and semispinalis capitis muscle. It then passes through the semispinalis capitis muscle and ascends to innervate the skin along the posterior part of the scalp to the vertex. It innervates the scalp at the top of the head, over the ear and over the parotid glands. After emerging from the suboccipital triangle obliquely between the inferior oblique and semispinalis capitis muscle, the GON then passes through the fascia of the trapezius muscle and pierces the semispinalis capitis muscle to ascend to innervate the skin along the posterior part of the scalp to the vertex. It innervates the scalp at the top of the head, over the ear and over the parotid glands.

The GON may be treated using the systems disclosed herein by creating a cooling zone at a GON block site The GON block site is normally selected based on: Arterial palpation; use of a Doppler flow probe, and sensory nerve stimulation. In addition, ultrasound visualization can be used to identify the nerve and recognition of anatomical variability in its course, division and relationship to surrounding structures. It is more difficult to visualize the GON at the Superior Nuchal Line due to shallow depth and smaller diameter.

FIG. 6 shows a typical GON block site 1. The GON block site 1 is shown at the superior Nuchal Line. Based on GON depth of ˜8 mm, devices as short as 6 mm can be used to access the Gon block site 1. The GON diameter at GON block site 1 is approximately 4.2 mm in diameter. The GON may have several branches at GON block site 1. Here, the GON is normally located ˜3.8 cm (1.5-7.5 cm) from the midline at a horizontal level between the external occipital protuberance and the mastoid process. The Gon block site 1 is normally identified by palpation or nerve stimulation, as the occipitalis muscle, splenius capitis muscle, and the trapezius muscle all attach at this line. The location of the GON for anesthesia or any other neurosurgical procedure has been established as approximately 2 cm lateral to the external occipital protuberance, and approximately 2 cm inferior.

An alternative GON block site 2 is shown as well. Based on the GON depth at GON block site 2, the nerve is likely too deep here for devices less than 12 mm. The nerve depth is approximately 17 mm. The GON diameter at GON block site 1 is approximately 4.8 mm in diameter. The GON block site 2 is relatively proximal to the superior nuchal line, at C2, superficial to the obliquus capitis inferior muscle. Since the GON block site 2 is relatively close to the vertebral artery, the procedure here should not be performed without ultrasound guidance.

FIG. 7 shows the location of the lesser occipital nerve (LON), which can also be treated using the systems disclosed herein. The LON arises from the lateral branch of the ventral ramus of the second cervical nerve, sometimes also from the third. This LON branch is occasionally derived from the GON. The LON curves around and ascends along the posterior border of the sternocleidomastoid. Near the cranium the LON perforates the deep fascia, and continues upward along the side of the head behind the auricula. The LON provides an auricular branch. Often, the LON varies in size, and is sometimes duplicated. The LON supplies the skin of the upper and back part of the auricula, communicating with the mastoid branch of the great auricular. The LON also supplies the skin and communicates with the GON, the great auricular, and the posterior auricular branch of the facial.

FIG. 8 shows a schematic illustration of the courses of the greater and lesser occipital nerves. The GON pierces the semispinalis capitis muscle and then travels in a superolateral direction. At the level of the occipital protuberance, the GON is approximately 3-4 cm lateral to the midline, and the greater and lesser occipital nerves are actually close to each other. The LON follows the posteromedial border of the sternocleidomastoid muscle and only crosses it after it has traveled superiorly.

FIG. 9 shows a schematic illustration of GON and LON treatment locations, illustrated by tips of the cannulas. The occipital nerve emergences 3 cm below 1.5 cm lateral from the occipital protuberance. A GON treatment location (left most) is shown above superior nuchal line, 2.5-3.0 cm lateral to external occipital protuberance, and 6-8 mm below skin. This location is medial to occipital artery, which is typically a reliable landmark for most patients. The GON treatment location is also palpable. A LON treatment location (right most) is located 2.5 cm lateral to the artery.

Methods can be implemented using one or more aspects of the system disclosed above for treatment of occipital neuralgia. Generally, at least one needle of a needle probe is placed proximate to the occipital nerve. The needle probe can include more needles, however only one is required. A treatment algorithm is then enacted to provide the needle with cooling fluid for a predetermined amount of time. Further, warming phases may take place before and after the cooling fluid is provided, however, the warming phases are not required for efficacy of treatment.

The treatment algorithm is configured to provide coolant long enough to remodel tissue of the occipital nerve and thereby mitigate symptoms of occipital neuralgia.

Needle probes for treating symptoms of occipital neuralgia are configured to access relatively deep locations within tissue to treat deeper nerves require longer needles. Longer needles of a multi-needle needle probe may also require a smaller gauge (larger diameter) so that each needles has sufficient rigidity to maintain consistent spacing when placed deep in the tissue, but not so large as to create significant mechanical injury to the skin and tissue when inserted (e.g. larger than 20 ga). Alternate configurations of the needle probe have 2 or more needles spaced generally 3-7 mm apart of lengths ranging up to 20 mm or greater, typically of 25 gauge or 23 gauge. Single needle configurations can be even longer and may require active nerve location such as ultrasound or electrical nerve stimulation to guide placement of the needle. A long, single needle does not require the skin protection elements of the (e.g. active heating of the skin warmer and/or cladding) found in the shorter needle as the cooling zone can be placed sufficiently deep below the dermis to prevent injury.

Devices used for the treatment of symptoms of occipital neuralgia were configured with 3 needles each of 27 gauge, 6 mm length, and 2 mm spacing between needles. Although this configuration was effective in some cases, it is believe that a different design may be more effective and/or be easier to use. Where the GON is generally larger in diameter than the LON and is found deeper below the dermis, a cryoprobe with longer needles and a wider spacing between needles is preferable. A needle probe may include needles placed 5-8 mm apart and 12 mm in length or greater, which would more effectively treat the GON. Additionally the GON and other nerves become more superficial and smaller in diameter as it travels in the inferior direction, thus a cryoprobe can be optimized for the treatment of a nerve in both length and needle spacing depending on the nerve and treatment location. With increased spacing, system modifications may be required to increase cooling power to ensure that the target temperature is reached between adjacent needles to achieve creation of a preferred cooling zone volume, also referred to herein as a cryozone. For example, in some embodiments, devices and treatment cycles may be configured to generate cryozones (defined by a 0 degree isotherm) having a cross-sectional area of approximately 14-55 mm² (e.g., 27 mm²). Optionally, the devices and treatment cycles may be configured to generate cryozones having a volume of approximately 65-125 mm³ (e.g., 85 mm³). This could be done by increasing the flow rate of the cryogen or by changing to a cryogen with more cooling power. Power to the heater can also be decreased, minimized, or eliminated, since the location is not generally associated with aesthetics, thus, allowing wider spacing between needles.

Variability from patient to patient in the depth of the occipital nerve created challenges with early treatments. Using PENS to determine the approximate location and depth of the nerve and then by placing a 12 mm needle probe to that approximate location and depth, either by partially inserting it or by compressing the tissue (by pressing hard), the PENS guided treatments were generally more successful.

A single needle probe configuration (e.g. 1×90 mm) can also be used, optionally with the help of ultrasound nerve location or percutaneous electrical nerve stimulation (PENS) to place the single needle adjacent to one side of the nerve. This configuration would be helpful for treating nerves that are very deep, i.e., greater than 15 mm below the dermis. Larger sized occipital nerves may require treatment from both sides to make sure that the cold zone created by the needle fully covers the nerve. Adjacent treatments placing a needle to either side of the nerve during two successive treatment cycles will still provide an effective treatment of the entire occipital nerve cross-section.

Other variations are within the spirit of the present disclosure. Thus, while the invention is susceptible to various modifications and alternative constructions, certain illustrated embodiments thereof are shown in the drawings and have been described above in detail. It should be understood, however, that there is no intention to limit the invention to the specific form or forms disclosed, but on the contrary, the intention is to cover all modifications, alternative constructions, and equivalents falling within the spirit and scope of the invention, as defined in the appended claims. 

What is claimed is:
 1. A system for alleviating occipital neuralgia, the system comprising: a needle probe comprising a pair of needles, each of the needles having a proximal end, a distal end, and a needle lumen therebetween, the needles configured for insertion proximate to a location of an occipital nerve, the needles being spaced apart to flank at least a portion of the occipital nerve, wherein the pair of needles are spaced apart by at least 2 mm to flank the portion of a greater occipital nerve; a cooling fluid supply lumen extending distally within each of the needle lumens to a distal portion of the needle lumens; a cooling fluid source couplable to the cooling fluid supply lumens to direct a fluid flow into the needle lumens; a heating element coupled with the proximal ends of the needles, the heating element configured to deliver heating phases to skin of the patient; a controller having at least one processor configured to implement an occipital neuralgia treatment algorithm for controlling the cooling fluid source so that liquid from the fluid flow vaporizes within the needle lumens to provide a treatment cycle to the greater occipital nerve such that the occipital neuralgia is mitigated, wherein the processor is configured to control the fluid flow and the heating element in response to operator input, the processor configured to provide the treatment cycle in response to the operator input, the treatment cycle comprising at least one heating phase and one cooling phase, and wherein the processor is configured to monitor power draw from the heating element during the treatment cycle; and a temperature sensor coupled with the proximal ends of the needles, wherein the processor is configured to generate a difference between a temperature measured by the temperature sensor and a normal temperature condition, whereby the processor activates an error flag and suspends the treatment cycle in response to the difference indicating an out of normal condition.
 2. The system of claim 1, wherein the occipital neuralgia treatment algorithm is configured to cause the needle probe to generate a cryozone having a volume of 65-125 mm³.
 3. The system of claim 1, wherein the pair of needles are spaced apart 2-8 mm to flank the portion of the greater occipital nerve.
 4. The system of claim 1, wherein the pair of needles have a length in a range of 3 mm to 15 mm.
 5. The system of claim 1, wherein the pair of needles are spaced apart 3-7 mm to flank the portion of the greater occipital nerve.
 6. The system of claim 1, wherein the pair of needles are spaced apart 5-8 mm to flank the portion of the greater occipital nerve.
 7. The system of claim 1, wherein power draw from the heating element is used to at least one of characterize tissue type, perform diagnostics, provide feedback for the occipital neuralgia treatment algorithm, indicate a malfunction, or indicate whether the needle probe is incorrectly positioned.
 8. The system of claim 1, wherein the processor is further configured to compare a duration of the treatment cycle to a threshold value and deactivate the heating element if the duration exceeds the threshold value.
 9. A system for alleviating occipital neuralgia, the system comprising: a needle probe comprising a pair of needles, each of the needles having a proximal end, a distal end, and a needle lumen therebetween, the needles configured for insertion proximate to a location of an occipital nerve, the needles being spaced apart to flank at least a portion of the occipital nerve, wherein the pair of needles are spaced apart by at least 2 mm to flank the portion a lower occipital nerve a cooling fluid supply lumen extending distally within each of the needle lumens to a distal portion of the needle lumens; cooling fluid source couplable to the cooling fluid supply lumens to direct a fluid flow into the needle lumens; a heating element coupled with the proximal ends of the needles, the heating element configured to deliver heating phases to skin of the patient; a controller having at least one processor configured to implement an occipital neuralgia treatment algorithm for controlling the cooling fluid source so that liquid from the fluid flow vaporizes within the needle lumens to provide a treatment cycle to the lower occipital nerve such that the occipital neuralgia is mitigated, wherein the processor is configured to control the fluid flow and the heating element in response to operator input, the processor configured to provide the treatment cycle in response to the operator input, the treatment cycle comprising at least one heating phase and one cooling phase, and wherein the processor is configured to monitor power draw from the heating element during the treatment cycle; and a temperature sensor coupled with the proximal ends of the needles, wherein the processor is configured to generate a difference between a temperature measured by the temperature sensor and a normal temperature condition, where by the processor activates an error flag and suspends the treatment cycle in response to the difference indicating an out of normal condition.
 10. The system of claim 9, wherein power draw from the heating element is used to at least one of characterize tissue type, perform diagnostics, provide feedback for the occipital neuralgia treatment algorithm, indicate a malfunction, or indicate whether the needle probe is incorrectly positioned.
 11. The system of claim 9, wherein the processor is further configured to compare a duration of the treatment cycle to a threshold value and deactivate the heating element if the duration exceeds the threshold value.
 12. The system of claim 9, wherein the pair of needles are spaced apart 3-7 mm to flank the portion of the lower occipital nerve.
 13. The system of claim 9, wherein the pair of needles are spaced apart 5-8 mm to flank the portion of the lower occipital nerve.
 14. The system of claim 9, wherein the pair of needles have a length in a range of 3 mm to 15 mm. 